1. Field of the Invention
The present invention relates to color filters used in color display devices and the like and methods for manufacturing the same. In particular, the present invention relates to a color filter suitable for color liquid crystal display devices which are used for color television sets, car television sets, personal computers and game machines, a liquid crystal display device using the color filter, methods for manufacturing them, and an ink for ink jet recording which is used in these methods.
2. Description of the Related Art
In recent years, the demand for liquid crystal displays and particularly color liquid crystal displays has increased with growth of the personal computer market and especially the portable personal computer market; consequently, cost reduction of liquid crystal displays and particularly expensive color filters has been greatly needed for further growth of the market. Various methods, as described below, have been attempted in order to achieve cost reductions while satisfying the characteristics required for color filters. No methods satisfying all of the required characteristics, however, have been proposed.
The first attempted method is a staining process, in which a water soluble polymer as a staining material is applied on a glass substrate, the coating film is subjected to photolithography to form a given pattern, and the substrate is dipped into a staining bath to form a colored pattern. These procedures are repeated three times to form red (R), green (G) and blue (B) colored layers.
The second attempted method is a pigment dispersion process which has taken the place of the staining method, recently. In this process, a photosensitive resin layer containing dispersed pigment is formed on a substrate, and subjected to patterning to obtain a given pattern. The procedures are repeated three times to form R, G and B colored layers.
The third method is an electrodeposition process, in which a transparent electrode pattern is formed on a substrate, and the substrate is dipped into an electrodeposition solution containing a pigment, a resin and an electrolytic solution to electro-deposit a first color. The procedures are repeated three times to form R, G and B colored layers, followed by baking.
The fourth method includes dispersing a pigment in a thermosetting resin and printing the dispersion. The procedures are repeated three times to form R, G and B colored layers and the substrate is heated to cure the thermosetting resin. Protective films are generally formed on the colored layers in all the processes.
One of common problems of these processes is high production cost due to triplicated coloring or staining procedures which are unavoidable in order to form R, G and B colored layers. Further, such repeated procedures result in a decreased yield. In the electrodeposition process, the shape of the formable pattern is limited, and thus a color filter prepared by this process is not applicable to thin film transistor (TFT) substrates in the current technology. The printing process is not suitable for fine pitch patterning due to inferior resolution and smoothness.
In order to overcome these problems, methods for manufacturing color filters by means of ink jet processes are disclosed in Japanese Patent Laid-Open Nos. 59-75205, 63-235901 and 1-217320. These methods, however, are not satisfactory.